Conventions Used Vishay Semiconductors Conventions Used in Presenting Technical Data SYMBOLS AND TERMINOLOGY (ALPHABETICALLY) A Radiant sensitive area sr Steradian C Capacitance T Period (duration) °C Celsius T Temperature Cj Junction capacitance t Time Ck Coupling capacitance Tamb Ambient temperature (range) d Distance Tcase Case temperature EA Illumination at standard illuminant A td Delay time Ee Irradiance (at a point of a surface) tf Fall time Ev Illuminance (at a point of a surface) Tj Junction temperature f Frequency toff Turn-off time Ie Radiant intensity (of a source in a given direction) ton Turn-on time IF Forward current continuous tp Pulse duration IFM Peak forward current tpi Input pulse duration IOH High level output current tpo Output pulse duration Iph Photocurrent (photoelectric current) tr Rise time Ira Reverse light current ts Storage time Iro Reverse dark current Tsd Soldering temperature ISD Supply current in dark ambient Tstg Storage temperature range ISH Supply current in bright ambient VCEsat Collector emitter saturation voltage Iv Luminous intensity (of a source, in a given direction) VEBO Emitter base voltage, open collector K Kelvin VECO Emitter collector voltage, open base lm Lumen VF Forward voltage lx Lux VO Output voltage NEP Noise equivalent power VOH Output voltage high Pdiss Power dissipation, general VOL Output voltage low Ptot Total power dissipation VR Reverse voltage RIO Input/output isolation resistor VS, VCC Supply voltage Ris Isolation resistance ϕ = α/2 Angle of half sensitivity, Angle of half intensity RL Load resistance ϕ1/2 Angle of half transmission distance RthJA Thermal resistance, junction to ambient λ Wavelength, general RthJC Thermal resistance, junction to case λ0.5 Range of spectral bandwidth (50 %) S Sensitivity, absolute λp Wavelength of peak sensitivity or peak emission s(λ) Absolute spectral sensitivity at a wavelength λ Δλ Spectral half bandwidth s(λ)rel Spectral sensitivity, relative Φe Radiant flux, radiant power s(λ0) Spectral sensitivity at a reference wavelength λ0 Ω Solid angle s(λp) Spectral sensitivity at a reference wavelength λp Document Number: 84697 Rev. 1.5, 21-Aug-08 www.vishay.com 7